Exhaust gas properties

[gcomyn]

I'm working on a calculation of diesel exhaust system back pressure and was wondering if there were any values for gas densities and viscosity? Or are the properties for air at exhaust temperatures close enough?

 

[Feric]

Hi there:

When considering Diesel engine operation, an ideal cycle approach might be sufficient to get you initial density values.

Therefore, I would suggest that you use ideal gas state equation when calculating density values:

pv = RT

p/density = RT

Go with air properties -- ignore the impact of fuel on the working fluid (combustion products).

Thanks,

Gordan

http://engware.i-dentity.com

 

[SomptingGuy]

For the products of lean/stoich combustion (e.g. your average diesel and/or gas these days), the mean molecular weight is that of air (28.8 ish). No need for compensation. However, Cp will vary if you are doing compressible flow calc.

 

[21121956]

Hello everybody:

Hi gcomyn, this site has been widely advised in the Eng-Tips Forums and, certainly, is a good one.

http://www.hrsgdesign.com/design0.htm

When open, ---> "Process" ---> Thermal properties of flue gas.

Good luck !

 

[turbomotor]

My Pratt & Whitney Aeronautical Handbook has gas properties for the combustion products of paraffin hydrocarbon (CH(2n+2)) in air and at 100% theoretical air (stoichiometric), 200% theoretical air (probably close to actual diesel engine operation at rated power), and 400% theoretical air.

The info is used by turbine engine engineers, and my guess is that you should look for turbine engine data resources to get similar data.